Nutrition - Histology + Mammlian Digestive System Flashcards
Structure of tissue in gastrointestinal duct
Epithelial tissue: separate muscular tissue + absorption
Mucosa: covered by a layer of epithelial cells; some of these produce mucus and others are responsible for the final stages of digestion and absorption of nutrients.
Muscularis mucosa: a thin layer of muscle involved in moving the inner wall of the gut.
Submucosa: generally carries the main arterioles and venules. It may also contain glands.
Longitudinal and circular muscle layers: responsible for peristalsis. Vertical + circular contraction
Serosa: a layer of connective tissue carrying blood vessels, lymphatic vessels and nerves. Secrete mucus to lubricants gut lining
Diagram of gastrointestinal tract
https://resource.download.wjec.co.uk/vtc/2020-21/el20-21_20-6/stomach-and-intestines.jpg
Villi structure in small intestine
-having folds in the wall to increase surface area
-the inner surface is further folded to form millions of structures called villi
-the surface of the epithelial cells covering the villi is further folded to form many microvilli.
Adaptation
rich capillary network to absorb and remove products of digestion and maintain a concentration gradient
lacteals to absorb the products of fat digestion and maintain a concentration gradient
they are thin to reduce diffusion distance
microvilli increase surface area
epithelial cells contain large numbers of mitochondria to provide the ATP for active transport.
Diagram of villi
https://resource.download.wjec.co.uk/vtc/2020-21/el20-21_20-6/villus.jpg
Diagram of pH at different stage of digestive system
https://resource.download.wjec.co.uk/vtc/2020-21/el20-21_20-6/ph-gut.jpg
Digestions of biological molecule
Starch -> maltose
-amylase in mouth or small intestine
-maltase, lactase, sucrase in epithelial cell of villi
Protein -> polypeptide chain
-exo-peptidase : pepsin in stomach or trypsin in small intestine (8 pH)
-endo-peptidase: into amino acid in epithelial cell of villi
Lipid -> glycerol + fatty acid
-lipase in small intestine
-bile emulsify = SA
Absorption of molecules
Glucose + amino acid
-active transport or diffuse into capillary
-to liver via hepatic portal vein
Glycerol + fatty acid
-pass into lacteal -> lymphatic system then to blood
Dentition of herbivore
Incisor - trim grass
Horny pad - trim grass
Diastema - split ducal cavity for cutting + grinding
Premolar + polar rigid - grind grass
Jaw can move side to side - grinding motion
Dentition of carnivore
Incisor - to tear off flesh
Canine - grip onto prey
Carnassial teeth - chew bone + flesh unevenly shaped
Jaw can only move vertically- strong biting force
Diagram of dentition
https://imgv2-2-f.scribdassets.com/img/document/510642049/original/ce37dd794f/1?v=1
Carnivore digestive system
Short intestine compare to herbivore
-protein + fat easier to digest
Caecum small
Non-ruminant herbivore digestive system
Longer caecum - contain mutualistic bacteria to digest cellulose
Longer large intestine to absorb water
Caecum after small intestine - nutrient digested at caecum can’t be absorbed - some reingest waste of not
Ruminant herbivore digestive system
Same as last one but:
3 chambers from oesophagus (rumen)
-bacteria to digest cellulose
-regurgitate food for further fermentation of callouses
-digest again at true stomach
-more efficient at digesting cellulose
Diagram of different animal digestive system
https://resource.download.wjec.co.uk/vtc/2020-21/el20-21_20-6/zoology.jpg
